preprint to be published in the proceedings of the 26 th European Photovoltaic Solar Energy Conference, 5 9 September 2011, Hamburg, Germany

Transcription

1 HYBRID PV-WIND-RENEWABLE METHANE POWER PLANTS A POTENTIAL CORNERSTONE OF GLOBAL ENERGY SUPPLY Ch. Breyer 1,2,3, S. Reke 4, M. Sterner 5, J. Schmd 5 1 Q-Cells SE, Sonnenallee 17-21, Btterfeld-Wolfen OT Thalhem, Germany, 2 Unverstät Kassel, Wlhelmshöher Allee 73, Kassel, Germany, 3 now wth: Rener Lemone Insttut ggmbh, Ostendstraße 25, Berln, Germany, Phone +49 (0) , E-mal: chrstan.breyer@rl-nsttut.de 4 Solar Fuel GmbH, Hessbrühlstr. 15, Stuttgart, Germany, Phone +49 (0) , E-mal: reke@solar-fuel.net 5 Fraunhofer IWES, Köngstor 59, Kassel, Germany, Phone +49 (0) , E-mal: mchael.sterner@ wes.fraunhofer.de, juergen.schmd@wes.fraunhofer.de ABSTRACT A 100% renewable power supply on a low cost bass s prerequste for a sustanable global development. Solar and wnd resources are abundantly avalable on earth enablng the use of photovoltac (PV) and wnd energy technologes on a large scale n most regons n the world. Ths paper ams at nvestgatng a global energy supply scenaro based of PV and wnd power supported by an approprate energy storage nfrastructure. Frst results for the degree of complementarty of PV and wnd power supply are presented and the need of approprate energy storage solutons s dscussed. We present the renewable power methane (RPM) storage opton and dscuss the varous ntegraton optons of hybrd PV-Wnd-RPM power plants. Based on the levelzed cost of electrcty (LOCE) approach and on cost assumptons for the year 2020, hybrd PV-Wnd-RPM power plant economcs are derved on a global scale and dscussed n more detal for an exemplary ste n Chna. Frst estmates for the global energy supply potental of hybrd PV-Wnd-RPM power plants show both, rapdly ncreasng compettveness and low dstances between the centres of demand and least cost energy supply, whch s complemented by abundant resource avalablty. In concluson, hybrd PV-Wnd-RPM power plants are a potental cornerstone of the global energy supply n the next decades. Keywords Hybrd Power Plant, Renewable Power Methane, Fuel-Party, Economc Analyss, Energy Optons, PV Markets 1 Introducton Photovoltac (PV) s the fastest growng electrcty generaton technology n the world.[1] Second fastest growng electrcty opton s wnd power.[2] Global solar and wnd resource assessment clearly documents sustanable and the by far hghest resource potentals for PV and wnd of all power technologes avalable to the market. However the fluctuatng solar and wnd resources make t necessary to use fossl fuel power plant or storage capactes for balancng reasons. An emergng storage opton s the renewable power methane (RPM) storage technology. The purpose of the presented work s a frst analyss of the global economc mpact potental of RPM storage by the end of the 2010s whch would enable hybrd PV- Wnd-RPM power plants establshng a fully dspatchable power supply based on fluctuatng wnd and solar resources. Ths paper presents an overvew on the renewable power methane storage technology (secton 2), solar and wnd resource avalablty (secton 3) and economcs of system components (secton 4). The global economcs of hybrd PV-Wnd-RPM power plants are estmated for the year 2020 (secton 5) and presented n a more detaled vew for the exemplary potental market n Chna (secton 6). The global power supply potental of hybrd PV-Wnd- RPM power plants s dscussed (secton 7) and the results are summarzed by the concluson (secton 8). Ths conference contrbuton presents technologcal and conceptual results of Solar Fuel and Fraunhofer IWES and economc results of Q-Cells research. Intally the research at Q-Cells was focussed on hybrd PV-Fossl power plants [3-5] resultng n qute smlar economcs for PV and wnd power plants by the end of the 2010s for many stes n the world [6]. The complementary characterstcs of PV and wnd power avalablty [7] generated the nsght of frstly, takng nto account both major new renewable power technologes and secondly, ntegratng the seasonal RPM storage technology for a 100% renewable power soluton. All these mentoned topcs are part of a more comprehensve work on the economcs of hybrd PV power plants.[6] 2 Renewable Power Methane Storage The current mx of rsks,.e. mpact of clmate change, dmnshng fossl fuels and nuclear hazards, nduces enormous pressure for restructurng the global energy supply, whch s dependent to about 87% on exactly these rsk creatng energy sources [8]. The only sustanable energy pathway follows the varous renewable energes. A stable power supply needs to be based on full daly and especally seasonal adapton of renewable power supply to the load demand n the grds. The balance of seasonal renewable power supply and load demand s challengng, snce both hydro storage dams and bomass power supply are very lmted due to geographc and resource competton constrants.

2 Addtonally, the major renewable power supply optons are represented by solar PV and wnd power (secton 3), whch are both fluctuatng. Hence, flexble power generaton unts are needed for balancng resource avalablty and load demand for a stable electrcty supply. Ol, natural gas and coal fred power plants can serve as flexble power generaton unts. However, the assocated greenhouse gas emssons and dmnshng fossl fuel resources allow these conventonal power technologes only for a lmted functon n a transton phase pror to a fully renewable power supply. Beyond that, fossl natural gas fred power plants, techncally better called methane power plants, can also be fred by RPM, whereas RPM can be produced by renewable power, ar and water as nput sources. The requred seasonal storage of methane s already appled today. As a consequence, the power grd and natural gas grd become connected enablng an energy flow n both drectons (Fgure 1). Fgure 1: Hybrd PV-Wnd-RPM power plant embedded n the power grd and the natural gas grd. Energy flows are possble n both drectons,.e. storage of electrcty n the natural gas nfrastructure and converson of RPM nto electrcty. Three elementary core processes are needed for RPM: electrolyss (converson of electrcty and water nto hydrogen and oxygen), CO 2 supply (e.g. extracton from ambent ar va dalyss process, by-product of bogas plants, fossl fuel power plants or ndustral processes) and methanaton (converson of hydrogen, carbon doxde and electrcty nto methane and water).[9] A good overvew on the RPM concept, the relevant components and the energy system ntegraton s gven by Sterner [9], Specht et al. [10,11] and Sterner et al. [12]. The RPM technology s scaled up towards an ndustral sze n the next years,.e. the exstng 25 kw el demonstraton faclty s currently expanded to a 250 kw el plant, and untl 2015 the next expanson s planned to 6.3 MW el and up to 20 MW el on a modular bass. The frst core process s the electrolyss convertng renewable electrcty and water nto hydrogen and oxygen (Fgure 1). Several electrolyss technologes are avalable enablng energy converson effcences of up to 80%. The technology has been used for decades and can be operated at varous pressures, temperatures and s scalable for ndustral applcatons n the range of some kw to MW.[9] The hydrogen s used n the methanaton (Sabater process), the second core process, to convert hydrogen and carbon doxde to methane and water (Fgure 1). The energy converson can reach effcences up to 85% n a catalytc exothermal process on a temperature level of C and a pressure of bars.[9] Several CO 2 sourcng routes are avalable, e.g. byproduct of bogas plants, fossl fuel power plants or ndustral processes, however the most elegant way s the extracton of CO 2 from ambent ar. Several processes are known for extractng CO 2 from ambent ar [9], whereas n the followng the focus s put on the energy effcent ZSW process based on absorpton and electrodalyss.[13] For producng 10 MJ th RPM, 16 MJ el are requred for the electrolyss process ncludng the methanaton process plus further 4.8 MJ el n case of extracton of CO 2 from ambent ar. Ths translates nto a renewable electrcty to RPM converson effcency of about 63% excludng energy for CO 2 sourng. Specfc energy consumpton of the dalyss process extractng CO 2 from ambent ar corresponds to a vrtual effcency of about 77%. Thus, RPM based on CO 2 extracton from ambent ar can be generated on an effcency level of about 49%, whereas the exothermc methanaton process supples hgh temperature process heat that mght be used for other purposes. About 50% of the electrc energy can be chemcally stored n RPM and may afterwards be used for all purposes fossl natural gas s used for. In case of burnng RPM n modern gas power plants,.e. n 58% effcent combned cycle gas turbnes (CCGT), the full cycle effcency would be about 37% (CO 2 avalable on ste) and 29% (CO 2 extracton from ambent ar). Ths full cycle storage effcency s rather low and nduces hgh specfc cost for such stored electrcty, however an easy to use seasonal energy storage would be enabled and the entre natural gas nfrastructure could be used. Lookng for alternatve solutons, there are few and very lmted seasonal electrcty storage optons, n partcular for large scale energy storage (Fgure 2). Fgure 2: Overvew on major electrcty storage technologes n dependence on energetc storage capacty and charge cyclng. RPM (denoted as Solar Fuel) s one of only few seasonal storage optons for large scale energy storage. Pumped hydro storage s the most preferred energy storage on the power plant and power grd level due to relatvely low cost, large energy storage reservors and a hgh flexblty n swtchng from charge to dscharge

3 operaton mode. However, geographc prerequstes of substantal dfference n alttude and avalable topographc stes lmt ths large scale energy storage. The example of Germany emphasses the already exstng methane storage capacty, snce 0.04 TWh pumped hydro storage and 217 TWh natural gas storage capactes are currently avalable. A seasonal energy storage would also nduce hgh storage cost due to a respectve low cycle frequency. The remanng two seasonal storage solutons are hydrogen and methane. Seasonal storage on RPM bass mght be preferred due to hgher storage effcency and already exstng transport nfrastructure n most regons n the world plus avalable energy convertng unts, lke power plants, heatng for houses, powerng the transport sector and usng RPM n the chemcal ndustry. Based on the new lnk power-to-gas, 100% renewable energy supply systems are desgned (Fgure 3). The key elements are drect renewable power generaton (man prmary energy source ), renewable electromoblty [14], heat pumps, RPM and overcomng tradtonal bomass. By ntegratng smart power networks, heat networks and natural gas networks, a full renewable energy supply s enabled. Several 100% renewable energy systems based on hybrd PV-Wnd-RPM plants are presented, reducng global energy-related CO 2 emssons by 95%. One new key element s the mutual lnkng of power and gas networks. Fgure 3: Hybrd PV-Wnd-RPM plant (Fgure 1) as the ntegral centrepece of a future sustanable energy supply system.[9] The four man energy systems are ntegrated and postvely nfluenced by renewable power methane,.e. power network, natural gas network, heat network and transportaton network. Several ntegrated concepts wth CO 2 from ar, bomass, ndustral processes and fossl fuels are desgned. In ths way, renewable power can be stored n the natural gas network and used temporarly and spatally flexble for balancng power and long-term power storage, for process heat and for (long-dstance) transportaton wth a hgh-energy densty CO 2 -neutral energy carrer. The major advantage versus hydrogen s the use of the exstng nfrastructure. Hydrogen s stored n CO 2 and made thus avalable as natural gas substtute. RPM can be produced bascally anywhere where water, ar (CO 2 ) and renewable power (wnd, solar, hydro) are avalable and thus decreases dependence on fossl fuels mport and the need for new transmsson lnes by usng exstng gas grds. It can recycle CO 2 n the energy system by CO 2 capture from combuston or by the use of the generated O 2 for combuston of RPM n the oxyfuel process n combned cycle plants. Ths new approach can even act as carbon snk n combnaton wth CO 2 storage and thus create a carbon snk energy system. 3 Solar and Wnd Resource Avalablty The total and global prmary energy demand has been about 151,200 TWh th n the year 2008,.e. about 17 TW of contnuous energy flow.[8] However, substantal amount of ths prmary energy demand s wasted n neffcent energy use based on burnng fuels,.e. the drect use of valuable electrcty would reduce the aforementoned energy flow to about 11.5 TW provded for nstance by solar PV or wnd power.[15] The global energy supply potental of PV and wnd power exceeds by far ths energy demand of manknd. The techncal energy potental of solar PV and wnd s assessed dfferently by varous authors but always by factors or orders hgher than total global energy demand. In 1978 Wengart estmated the solar PV potental energy flow usable for manknd beng hgher than 100 TW.[16] In 2003, the German Advsory Councl on Global Change derved a harvestable energy flow potental for wnd power of about 90 TW and a practcally unlmted potental for PV.[17] However, these numbers have been adjusted n 2011 to a techncal potental of about 54 TW for wnd power and about 8,900 TW for solar energy and, thus, also for PV.[18] In the 2008 study energy [r]evoluton by Greenpeace, the utlzable energy flow has been estmated to about 35 TW for wnd power and 150 TW for PV.[19] Also n 2008, Sawn and Moomaw estmated the energy flow potental to about 145 TW for PV and about 55 TW for wnd power.[20] In 2009, Lu et al. estmated the energy flow for wnd power to about TW.[21] Jacobson and Delucch derved an energy flow of TW for wnd and 580 TW for PV.[15] In 2011 the IPCC derved a theoretcally utlzable energy flow of about 190 TW for wnd power and about 120,000 TW for PV.[22] Other authors clearly ponted out that wnd and solar energy wll become the backbone of the global energy supply and that ths could happen already before 2030.[23] The nsght that establshng a solar powered socety s necessary, lays many decades n the past and was emphaszed for nstance by Hubbert already n 1949.[24] The three major power technologes n relaton to mnmsed fully loaded socal cost are solar PV, wnd power and hydro power (secton 4). But only solar PV and wnd power have access to nearly abundant resources, whereas the solar resource s the most homogeneous dstrbuted energy source n the world. It mght be consdered as a godsend that the two least cost energy optons for the 21 st century are fully complementary to each other.[7] A frst global analyss of the complementary

4 characterstcs of PV and wnd power plants gves plenty of ndcatons that these two major renewable power technologes complement each other to a very large extent (Fgure 4) and show nearly no competton due to the fundamental underlyng solar and wnd resources.[7] The degree of complementarty s measured by overlap full load hours (FLh),.e. the amount of power provded by PV and wnd power plants adjacent to each other n the same tme nterval. Typcally, the overlap FLh ndcate a good complementarty due to part load condtons of the respectve power plants. For extractng the amount of power beng problematc, the crtcal overlap FLh are defned,.e. the amount of power beng above the rated capacty of PV or wnd power per geographc unt and tme nterval. In these cases the renewable power mght be lost due to lmted power lne, balancng power plant or storage capactes. The frst nsghts n the analyss of the complementarty of PV and wnd power s depcted n Fgure 4. sector and maybe even for the chemcal ndustry va renewable power generated methane. In order to acheve a secure and stable power supply, balancng power plants are stll needed. Natural gas (NG) power plant capacty of more than 1,100 GW s nstalled worldwde [8] and s perfectly suted for power balancng purposes. Hybrd PV-Wnd-NG power plants are an excellent power plant opton n the years to come [5,6], but ths technologcal approach stll depends on fossl fuels. Greenhouse gas emssons of NG fred CCGT are n the range of gco 2 /kwh consderng the full lfe cycle, beng too much n a clmate change constraned world. Moreover, peak n conventonal ol producton s a matter of fact and t s only a queston of tme when peak n NG producton wll occur. Nevertheless, global nstalled NG nfrastructure mght be of utmost relevance for fghtng clmate change and dmnshng fossl fuel resources as bass for the RPM dffuson. 4 Economcs of System Components Ths secton focuses on the economcs of the core system components related to hybrd PV-Wnd-RPM-CCGT power plants under the technologcal frame condtons needed for RPM storage. Relevant system components to be analysed are 1-axs horzontal north-south contnuous trackng PV power plants (PV 1N), wnd power plants wth 150 metre hub heght (Wnd 150m), combned cycle natural gas power plants n the conventonal and carbon capture and storage (CCS) verson (CCGT and CCGT- CCS), hard coal power plants n the conventonal and CCS verson (coal and coal-ccs) and RPM storage composed by dalyss, electrolyss and methanaton unts. The precondtons for a successful hybrdzaton are gven for the hybrd power plants dscussed n ths paper but are dscussed elsewhere n detal.[5,6] Fgure 4: Rato of annual total (top) and crtcal (bottom) overlap full load hours of PV and wnd power to added up full load hours of both power technologes.[7] Assumptons are PV fxed optmally tlted power plants and wnd power plants wth 150 m hub heght. Calculatons are performed on a mesh of 1 x1 lattude and longtude and a one hour tme nterval for the year Power capacty of PV and wnd power s set to an equal value. Global average of the relatve total overlap full load hours s about 15%, whereas maxmum overlap s 25%. Crtcal overlap s sgnfcantly lower,.e. avalable power per coordnate hgher than rated power capacty of one power technology. Crtcal overlap FLh are worldwde below 9% and at most places even below 3% to 4%. Consequently, PV and wnd power plants are fnally no competton to each other. Moreover, t can be expected that the complementarty of PV and wnd power leads to a sgnfcant reducton n the amount of nvestment whch s needed for the energy system and wll enable the power sector to offer hghly compettve solutons for the heat and transportaton A cost model for all components of the hybrd PV-Wnd- RPM-CCGT power plant s used for the calculaton of levelzed cost of electrcty (LCOE) [25] for all coordnates by applyng local FLh for the PV and wnd component n combnaton wth FLh assumptons for the entre hybrd power plant. RPM storage s expected to be avalable on the large scale by the end of the 2010s, whereas frst CCS power plants, as a potental CO 2 source, mght be n the demonstraton phase at that pont n tme. Based on the avalablty of these two major relevant components for a broad hybrd PV-Wnd-RPM- CCGT power plant analyss the year 2020 s chosen for scenaro evaluaton. Besdes typcal captal expendtures (Capex) and operatonal expendtures (Opex), major cost postons are expendtures for fuel but not for related carbon emssons due to ether CO 2 free power supply or applcaton of CCS technques. Such derved LCOE make t possble to compare them to LCOE of other renewable and conventonal power plant technologes. Methodology of calculatng hybrd PV-Wnd-RPM LCOE s summarzed n Equaton 1: LCOE LCOE (Eq. 1a)

5 Capex crf Opex LCOE FLh WACC crf, el, el carbon GHG 1 WACC N 1 WACC 1 N, fx E D WACC k E D E D FLh PV, el Y ref PerfR E k D Opex,var FLh RPM, el FLhtotal, el FLhPV, el FLhW, el fuel fuel fuel PE th,, el (Eq. 1b) (Eq. 1c) (Eq. 1d) (Eq. 1e) (Eq. 1f) crudeol cf (Eq. 1g) Equaton 1: Levelzed cost of electrcty (LCOE) for hybrd PV-Wnd-RPM-CCGT power plants. Abbrevatons stand for: captal expendtures (Capex), annuty factor (crf), annual operaton and mantenance expendtures (Opex), annual fxed Opex (Opex fx ), varable Opex (Opex var ), annual full load hours of component (FLh,el ), fuel cost of component (fuel ), thermal energy converson factor of component (PE th, ), prmary to electrc energy converson effcency of component (η,el ), weghted average cost of captal (WACC), lfetme of component (N ), equty (E), debt (D), return on equty (k E ), cost of debt (k D ), reference yeld for a specfc PV system at a specfc ste (Y ref ), PV performance rato (PerfR), renewable power methane components (RPM), fuel cost of crude ol (fuel crude ol ), rato of fossl fuel to crude ol as couplng factor (cf ) and prmary to electrc energy converson effcency of component (η,el ). Components of the hybrd PV- Wnd-RPM-CCGT power plant are: PV fxed optmally tlted, PV 1-axs horzontal north-south contnuous trackng, Wnd 150 metre hub heght, RPM storage unts (dalyss, electrolyss, methanaton), combned cycle gas turbne (CCGT) and carbon capture and sequestraton (CCS). These components are compared partly or fully to natural gas (NG) fred CCGT-CCS and coal fred coal- CCS power plants. LCOE component of PV and wnd power plants s the captal cost, whereas conventonal fossl power plants are more dependent on the fuel cost n contrary to fossl CCS power plants showng a hgher dependence on captal cost. Fossl fuel cost s ndrectly coupled to the crude ol prce due to the specfc thermal energy [5] and tends to fluctuatons and long-term escalaton. Total FLh of the hybrd PV-Wnd-RPM-CCGT power plant are superposed by the renewable source,.e. PV or wnd or hybrd PV-Wnd, and the balancng CCGT whch receves the methane by the RPM component of the hybrd plant. The RPM s assumed to be generated by not needed excess electrcty and CO 2 ether by extracton of CO 2 from the ambent ar (dalyss) or provded by the carbon capture and storage (CCS) component of the CCGT plant. The dalyss and electrolyss components show lower FLh due to ther adapton to the avalablty of fluctuatng excess electrcty. However, the methanaton component can be run n baseload operaton modus due to nternal hydrogen storage. Some mnmum FLh are assumed for practcal reasons,.e. mnmum 500 FLh of CCGT component, mnmum 500 FLh of NG- CCS component, mnmum 500 FLh of crtcal PV and wnd overlap beng very conservatve (secton 3) and mnmum total 5,000 FLh of the hybrd PV-Wnd-RPM- CCGT power plant. The latter assumpton s rather conservatve, snce the global power plant capacty s operated for about 4,300 FLh n average [6]. The hybrd power plant n ths confguraton can use the RPM as both a daly but also a seasonal storage. PV and wnd power plants are on an excellent cost trend and are expected to acheve LCOE of about /MWh n regons of good resource qualty n the year 2020 (Fgure 5). Major advantage of the hybrd PV-Wnd power plant component are the hgher FLh compared to only one renewable power source leadng to benefcal total LCOE of the hybrd PV-Wnd-RPM-CCGT power plant. The scenaro assumptons for calculatng LCOE are summarzed n Table 1 and are based on experence curve assumptons for PV and wnd power plants [5,6]. Major Fgure 5: Hybrd PV-Wnd power plants characterzed by ther global LCOE (left) and FLh (rght) projected for the year Assumed hybrd PV-Wnd sub plants are 1-axs horzontal north-south contnuous trackng PV power plants and wnd power plants wth a hub heght of 150 m for the condtons of Table 1. The underlyng resource data are provded by NASA SSE 6.0 [26] but reprocessed and dscussed elsewhere [6,27].

6 PV 1-axs Wnd 150m CCGT Coal Renewable Power Methane n year 2020 N-S horz. hub heght conv. CCS conv. CCS Dal. Electrol. Methanaton Capex [ /kw] Opex fx [ /kw/y] Opex var [ /MWh el] plant lfetme [y] plant effcency (PR) [%] 80% 95% 58% 48% 44% 34% 78% 78% 82% fuel prce couplng [fuel/ol] % 80% 30% 30% n general remark WACC [%] 6.0% despte of hgher fossl rsk profle dentcal for comparson reasons exchange rate [USD/ ] 1.40 FLh Methanaton [h/y] 8000 baseload operaton FLh mn CCGT [h/y] 500 mnmum FLh of CCGT component of respectve hybrd RPM-CCGT plants FLh mn NG-CCS [h/y] 500 mnmum FLh of NG-CCS component of hybrd PV-Wnd-NG-CCS plants FLh mn overlap [h/y] 500 assumed tme resolved FLh overlap of PV and Wnd (conservatve) Table 1: Key economc assumptons of hybrd PV-Wnd-RPM power plants and competng power plants projected for the year Abbrevatons stand for: 1-axs horzontal north-south contnuous trackng (1-axs N-S horz), combned cycle gas turbne (CCGT), conventonal (conv), carbon capture and storage (CCS), captal expendture (Capex), operatonal expendture (Opex), performance rato (PR), weghted average cost of captal (WACC), full load hours (FLh), renewable power methane (RPM) and natural gas (NG). Data are taken from varous sources and n case of the non RPM components gven elsewhere [6]. Producton cost of RPM by PV and wnd power supply s vsualzed n Fgure 6 for extractng CO 2 from ambent ar and for CO 2 accessble by CCS. The calculatons are based on scenaro assumptons defned n Table 1 and vsualzed for respectve hybrd PV-Wnd plants n Fgure 5. Results for RPM producton cost based on PV and wnd FLh and LCOE show challengng cost levels even n regons of excellent resource avalablty. In case of extractng CO 2 from ambent ar, a cost level of about USD/barrel eq can be reached (Fgure 6). For CO 2 beng avalable due to CCS the cost level s equvalent to about USD/barrel eq (Fgure 6). However the cost level mght be not too hgh compared to typcal fuel prces n ndustral countres, snce 200, 300 und 400 USD/barrel eq are equvalent to desel prces of 0.90, 1.35 and 1.80 /l, excludng any knd of taxaton and subsdes. The technologcal route of RPM producton offers access to hghly valuable fuels n many regons n the world (Fgure 6), n contrast to today s fossl fuel resource avalablty. Based on a more homogeneous solar resource and wnd resource dstrbuton n the world, the perspectve s gven for an addtonal more homogeneously dstrbuted renewables sourced hydrocarbon fuel avalablty. 5 Hybrd PV-Wnd-RPM Power Plant Economcs Fgure 6: Cost of RPM producton for CO 2 from the ar (top) and suppled by CCS facltes (bottom) projected for the year Power supply by hybrd PV-Wnd power plants (Fgure 5) s assumed for the condtons of Table 1. Cost of RPM producton mght be at about 300 USD/barrel eq for CO 2 from ar and about 200 USD/barrel eq for CO 2 from CCS route (excludng CCS cost) at stes of excellent solar and wnd resources. RPM storage offers three key features: Frstly, drect renewable energy supply can be used to the maxmum possble extent, e.g. PV and wnd power. Secondly, storage can be charged by surplus energy n perods when renewable power n the grd exceeds load, n partcular for seasonal balancng. Thrdly, a stable power supply can be granted for the entre year. The remanng queston wll be whether t mght be economcally feasble to run hybrd PV-Wnd-RPM-CCGT power plants as the centrepece of such a potental fully stable and sustanable renewable electrcty future. Total LCOE of hybrd PV-Wnd-RPM-CCGT power plants for 5,000 FLh s calculated on bass of Equaton 1 and scenaro assumptons n Table 1 for the renewable

7 components 1-axs horzontal north-south contnuous trackng PV, wnd turbnes wth 150 meter hub heght and the hybrd composton of these two sub-plants for the two CO 2 source routes,.e. from ambent ar and accessble by CCS (Fgure 7). Fgure 7: Global LCOE of hybrd PV-Wnd-RPM power plants for CO 2 from ar (top) and for CO 2 from CCS route (bottom) projected for the year Power supply by hybrd PV-Wnd power plants (Fgure 5) s assumed and 5,000 FLh n total for the hybrd power plant for the condtons of Table 1. LCOE of hybrd PV-Wnd-RPM power plants mght be about 80 /MWh at stes of excellent solar and wnd resources, whereas the CO 2 from ar route could be slghtly lower n LCOE manly drven by challengng economcs of CCS facltes. The LCOE outcome of both CO 2 sourcng routes s nearly dentcal, whereas the CO 2 extracton from ambent ar seems to be slghtly lower n cost for the specfc scenaro assumptons (Fgure 7). From the PV pont of vew, the hybrd PV-Wnd sub-plant leads to lower LCOE for the total hybrd PV-Wnd-RPM-CCGT power plant compared to the PV-only or wnd-only varaton. Ths s caused by the benefcal effect of extended FLh on a renewable low cost bass thereby reducng costly RPM producton to a mnmum level.[6] In result, a hybrd PV-Wnd sub-plant reduces the total LCOE to a level of /MWh n regons of good and excellent solar and wnd resource avalablty, e.g. the US, Chle, Argentna, Bolva, some locatons n Europe, nearly the entre MENA regon, parts of Central Asa and Australa. Nearly dentcal LCOE results for hybrd PV-Wnd- RPM-CCGT power plants based on the two dfferent CO 2 sourcng routes (Fgure 7) are n contrast to the results of RPM producton costs (Fgure 6), where the CO 2 extracton from ambent ar route s found to be about 40% hgher n cost than the CO 2 accessble from CCS opton. Ths contradcton dssolves as the CCS system approach s sgnfcantly hgher n cost on the power plant level due to hgher Capex of the CCGT-CCS versus the CCGT power plant component and lower respectve prmary energy converson effcency of CCGT-CCS versus CCGT (Table 1). In short, extractng CO 2 from ambent ar s less costly than CCS technology. As a consequence hgher RPM producton cost of the ambent ar route s levelled out by benefcal power plant characterstcs of the CCGT component. Ths qute relevant result needs to be analysed n a much deeper and broader scope than possble n ths work. It mght be possble that the enormous nvestments n CCS technology could end up as stranded cost on a macro-

8 economc level, n partcular n case of lower total power generaton system LCOE of hybrd PV-Wnd-RPM- CCGT power plants usng CO 2 extracton from ambent ar versus fossl fuel powered CCS power plants. Enormous publc fnancal means are needed for establshng the CCS technology and nfrastructure, whch mght be superfluous not only n the end but rght from the begnnng of CCS dffuson. 6 Chna An Exemplary Potental Market Consderatons n the last sectons are focussed on least LCOE of respectve hybrd PV-Wnd-RPM-CCGT power plants n the global context. However, from the local pont of vew a more dfferentated analyss s very helpful for understandng the local cost and technologcal dynamcs. Key assumptons for ths consderaton are already defned n Table 1, whch are appled for power plant confguratons of 6,000 FLh and a fossl fuel prce range of USD/barrel eq. The sngle components for establshng respectve power plants are: fxed optmally tlted PV, 1-axs horzontal north-south contnuous trackng PV, wnd power wth 150 metre hub heght, conventonal NG-CCGT, NG-CCGT-CCS, conventonal coal wthout CCS, coal-ccs, RPM producton usng CO 2 extracted from ambent ar and by a cyclcal CCS route. Based on these nne components a varety of 24 hybrd PV-Wnd-RPM-CCGT power plants and fossl fuel fred power plants s analysed. These analyses can be performed for all coordnates represented by data ponts n the Fgures 5 to 7, but here, the analyss s exemplarly conduced for a plant ste north of Bejng n Chna close to Mongola (about 45.5 N/ E). The dynamcs of the dfferent power plant varatons for the exemplary plant ste are depcted n Fgure 8. The varatons are measured n LCOE but are dependent on the fossl fuel prce. The selected ste s characterzed by good solar and very good wnd resource condtons. denoted as SF. FLh of renewable sub-plants can be found n the fgure for the specfc ste. The fossl sub-plant optons are natural gas (NG) fred combned cycle gas turbne (CCGT) and coal fred power plants. The hybrd PV-Wnd components are characterzed n Fgure 5. Further assumptons for cost calculaton are taken from Table 1. The selected ste would allow for a fossl fuel prce decoupled power generaton for LCOE of about 88 /MWh suppled by a hybrd PV-Wnd-RPM-CCGT power plant usng CO 2 extracted from ambent ar. Breakeven of the hybrd PV-NG-CCGT power plant versus the NG-CCGT power plant s acheved at a fossl fuel prce of 90 USD/barrel eq at LCOE of about 65 /MWh. A hybrd PV-RPM-CCGT power plant s not compettve to a NG-CCGT power plant at a fossl fuel prce of 250 USD/barrel eq and would generate electrcty at a LCOE level of about 215 /MWh for the CCS CO 2 sourcng opton. Breakeven of the hybrd Wnd-NG-CCGT power plant versus the NG-CCGT power plant s acheved at a fossl fuel prce of below 50 USD/barrel eq at LCOE of about 38 /MWh. A hybrd Wnd-RPM-CCGT power plant s compettve to a NG-CCGT power plant at a fossl fuel prce of 150 USD/barrel eq and would generate electrcty at a LCOE level of about 100 /MWh for the CO 2 extracton from ambent ar opton. Breakeven of the hybrd PV-Wnd-NG-CCGT power plant versus the NG-CCGT power plant s acheved at a fossl fuel prce of about 60 USD/barrel eq at LCOE of about 50 /MWh. A hybrd PV-Wnd-RPM-CCGT power plant s compettve to a NG-CCGT power plant at a fossl fuel prce of 128 USD/barrel eq and would generate electrcty at a LCOE level of about 88 /MWh for the CO 2 extracton from ambent ar opton. Total LCOE party for hybrd PV-Wnd-RPM-CCGT and NG- CCGT-CCS power plants s gven for a fossl fuel prce of about 75 USD/barrel eq at a LCOE level of about 88 /MWh and for extractng CO 2 from ambent ar. The hybrd PV-Wnd-RPM-CCGT power plant acheves LCOE party to coal-ccs power plants for a fossl fuel prce of 110 USD/barrel eq at about 88 /MWh LCOE n case CO 2 s extracted from ar. The respectve party to coal wthout CCS s gven at a fossl fuel prce of about 230 USD/barrel eq at about 88 /MWh LCOE and for extractng CO 2 from ambent ar. Fgure 8: Hybrd PV-Wnd-RPM-CCGT and fossl fuel fred power plant LCOE dynamcs for a ste n Chna close to Mongola (about 45.5 N/ E) for 6,000 FLh and a fossl fuel prce range of USD/barrel eq n the year The renewable sub-plant optons are fxed optmally tlted PV (PV 0), 1-axs horzontal north-south contnuous trackng PV (PV 1Nc), wnd power wth 150 m hub heght (Wnd), hybrd fxed tlted PV-Wnd (PV 0-Wnd) and hybrd 1-axs trackng PV-Wnd (PV 1N-Wnd) sub-plants for the two CO 2 source optons of extractng CO 2 from ambent ar (ar) and CO 2 accessble by CCS (CCS), whereas RPM s The total power plant capacty already avalable n Chna by end of 2008 (Fgure 9) shows relatve lttle nvestments n NG-CCGT capactes n the last years. Therefore the upgradng potental for hybrd PV-Wnd- RPM sub-plants mght be lmted. However, the large coal and hydro power plant capacty should be taken also nto account n respect to hybrd PV-Wnd-Coal power plants [5] and hybrd PV-Wnd-Hydro power plants [6].

9 only slghtly lower n cost. It s not clear whether CCS technology wll be really avalable by 2020 or even n 2030, hence watng for ths route mght waste a lot of valuable tme. Concludng ths, hybrd PV-Wnd-RPM- CCGT power plants extractng CO 2 from ambent ar enable a 100% renewable power supply n many regons n the world and show favourable economc performance. Fgure 9: Overvew on annually new nstalled power plant capacty n Chna. Annual power plant capacty nvestments stll n operaton are sorted by power technology for the years 1970 to Data are taken from UDI World Electrc Power Plants database.[28] The hybrd PV-Wnd-NG-CCGT power plant s the least LCOE power plant for a fossl fuel prce of at least 140 USD/barrel eq at a begnnng LCOE level of about 60 /MWh. Below 140 USD the hybrd Wnd-NG-CCGT power plant s only 2 3 /MWh hgher n LCOE than coal wthout CCS. The hybrd PV-Wnd-RPM-CCGT power plant LCOE s about 88 /MWh, but cannot reach the least LCOE level below 250 USD/barrel eq. CCS technology s not needed for a compettve least LCOE system desgn. 7 Global Power Supply Potental Upgradng NG-CCGT power plants by hybrd PV-Wnd power plants typcally leads to lower LCOE for fossl fuel prces of about USD/barrel eq. In case of good avalablty of solar and wnd resources, the hybrd PV- Wnd-NG-CCGT power plant s very compettve from fossl fuel prces of USD/barrel eq onwards. The remanng natural gas fred n the NG-CCGT sub-plant stll leads to CO 2 emssons but the natural gas can be replaced by RPM, however t wll be hgher n cost than the natural gas opton n nearly all regons n the world and for fossl fuel prces up to 250 USD/barrel eq assumng no carbon emsson cost. The hybrd PV-Wnd-RPM-CCGT power plant extractng CO 2 from ambent ar s an excellent centrepece of a 100% renewable power supply, whch mght be establshed on a LCOE level of about /MWh n regons of very good avalablty of solar and wnd resources. In regons of good solar and wnd resources the LCOE ranges from about /MWh and for at least one good and one moderate resource the LCOE could be about /MWh. These LCOE levels are fully decoupled from fossl fuel mpacts and can be consdered to represent the full socal cost,.e. no further external cost create an addtonal fnancal burden. Moreover, no CCS route s needed. CO 2 extracton from ar leads n most cases to lower total LCOE and n cases of cheaper CCS CO 2 sourcng ths s The enormous solar and wnd resource potental (secton 3) lays the bass for analyses of the global energy supply potental of solar PV and wnd power. The last sectons clearly emphasse that 100% renewable energy supply s techncally feasble on bass of PV and wnd power usng RPM for storage purposes, n partcular for seasonal storage. Economc consderatons result n total power generaton cost of below 100 /MWh n many large regons spread over the world (secton 5). In realty more renewable energy sources can be used for power supply. An excellent example how such a fully renewable powered energy system could work has been analysed for the DESERTEC project.[29-32] Hstorc roots of the DESERTEC project were lad n the 1920s focussng hydro power [33,34] and n the 1930s already based on frst PV concepts lnked to power lnes [35,36] but have been changed n the 1980s to solar hydrogen [37,38] and n the 2000s to solar thermal power generaton (STEG), agan lnked to power lnes [29-32]. DESERTEC s based on all major renewable energy sources and the nterconnecton of centres of energy supply and centres of energy demand by hgh voltage drect current (HVDC) power lnes. Solar PV, solar thermal and wnd power are assumed to be major sources of power, whereas bomass and hydro power mght act as a renewable balancng power. The EU-MENA DESERTEC project ganed pace by the Desertec Industral Intatve lead by ndustry gants [39] and mght become a blueprnt for smlar nterregonal cooperaton n other parts of the world reachng a global power grd. The global energy supply potental for STEGs has already been analysed.[40] Ths analyss of global energy supply potental of solar electrcty generated only n regons of excellent solar resources,.e. at least 2,000 kwh/m²/y drect normal rradaton, clearly shows the true potental of solar power: 90% of world populaton could be suppled by solar power (solar PV and solar thermal) va HVDC power lnes not longer than 3,000 km. The ndcaton s hgh, that based on STEGs a nearly 100% renewable power supply could be establshed. However, the STEG economcs are not as favourable as the comparable ones for PV and wnd power. Therefore t mght be of very hgh relevance to perform a global energy supply potental for hybrd PV-Wnd-RPM power plants on bass of economc compettveness. The last sectons pont out that a 100% renewable power supply s economcally feasble at latest n the end of the 2010s n the regons of the world where at least good and very good solar and wnd resources are avalable. Key queston n ths secton s the global energy supply potental of hybrd RPM systems. The three major steps for answerng ths are: Frstly, t needs to be dentfed

10 where hybrd PV-Wnd-RPM-CCGT power plants are lower n cost than natural gas and coal fred CCS power plants, whch would be the major competng power plant technologes n a CO 2 constraned world. Secondly, t needs to be estmated how much energy can be provded by those regons. Thrdly, t needs to be evaluated how many people lve n those favourable regons and more relevant dependng on the dstance to those regons how many further people could be suppled. The regons of least LCOE for 100% renewable power plants on bass of PV, wnd, RPM and CCGT components are shown n Fgure 10 beng derved on bass of cost competton aganst NG-CCGT-CCS and coal-ccs power plants and shown for a fossl fuel prce of 150 USD/barrel eq. Fgure 10: Hybrd PV-Wnd-RPM-CCGT power plants of least local LCOE n competton to NG-CCGT-CCS and coal-ccs power plants for a fossl fuel prce of 150 USD/barrel eq operated 5,000 FLh n the year The renewable sub-plant optons are dentcal to Fgure 8 for the two CO 2 source optons of extractng CO 2 from ambent ar (ar) and CO 2 accessble by CCS (CCS), whereas RPM s denoted as SF. The hybrd PV-Wnd components are characterzed n Fgure 5. Further assumptons for cost calculaton are taken from Table 1. The regons of most compettve hybrd PV-Wnd-RPM- CCGT power plants are dstrbuted all around the world and comprse the regons of very good solar and wnd resource avalablty. The global energy supply potental of hybrd PV-Wnd-RPM-CCGT power plants can be roughly estmated. The detals for the calculaton are dscussed elsewhere [6]. Notably, good PV stes of about 2,000 FLh generate an annual electrcty amount of about 107 GWh/km², whereas the good wnd power stes of about 3,000 FLh generate an annual electrcty of about 56 GWh/km², hence the practcal specfc energy generaton densty of PV s by a factor of two hgher than that of wnd power. However, the entre ste need to be reserved more or less fully for a PV power plant, but the ste beneath the wnd turbnes can be used smlar to the purpose before, e.g. crop land, forests, etc. For a crude ol prce of about 150 USD/barrel eq, about 37 mllon km² fulfl the crtera of lower hybrd PV-Wnd- RPM-CCGT LCOE than comparable fossl fuel fred CCS power plants. Only 1.3% and 6.9% of that area would be needed to fully cover the current power and addtonal thermal energy demand by the hybrd PV- Wnd-RPM-CCGT approach. The number for the thermal energy s a worst case assumpton due to enormous effcency potentals. The requred thermal energy mght be by a factor of four too hgh, accordng to fundamental effcency reasons. For the worst case t s assumed that there s a converson of valuable electrcty to methane and then subsequent conversons for the varous thermal energy servces, lke transportaton, heatng, cookng, etc. However, t would be much more effcent to use the electrcty n a drect way lke electrc transportaton, electrc heatng and electrc cookng whch would be more effcent by roughly a factor of four, or even more. The numbers for some decades nto the future, based on a crude ol prce of 200 USD/barrel eq, would be 12 bllon humans, about 57 mllon km² of least local hybrd PV- Wnd-RPM-CCGT LCOE, 3.9% and 16.2% of that area needed for coverng the electrc and thermal energy demand and smlar effcency consderatons for the hybrd PV-Wnd-RPM-CCGT but also for the thermal energy demand. The area requrement mght not be as hgh as t appears, snce n the future 200 USD/barrel eq case only 11% of the earth s surface s classfed for excellent hybrd PV-Wnd-RPM economcs, enormous effcency potentals of about a factor of four n the thermal energy demand are to be realsed, the energetc wealth level of the EU today mght be too hgh for 12 bllon people and all technologes for the hybrd PV- Wnd-RPM-CCGT approach are stll sgnfcantly mprovable. In total, enormous amounts of energy under least local LCOE condtons are avalable for powerng the energy needs of the manknd wthout relevant sustanablty crtera restrctons, n partcular due to the fact that several other renewable power technologes are able to complement PV and wnd power, the two core power technologes n the years and decades to come. Besdes the enormous energy supply potental of the most compettve regons on LCOE bass n the world, t s of hghest nterest how many people lve n these regons and wthn what dstance the other part of manknd lves. Many people lve n the regons of least cost 100% renewable power supply based on PV and wnd power plants even for low fossl fuel prces. For fossl fuel prces of up to 50 USD/barrel eq about 500 mllon and about 800 mllon for up to 100 USD/barrel eq lve wthn 100 km dstance to the regons of least cost power supply. These numbers sharply rse for hgher fuel prces to about 1,200 mllon (150 USD/barrel eq ), 1,800 mllon (200 USD/barrel eq ) and 2,200 mllon (250 USD/barrel eq ). The aggregated populaton n dependence on the dstance to the least cost regons s depcted n Fgure 11 for varous fossl fuel prce levels. Power lnes can transmt electrcty over several thousand klometres very effcently. Dstances more than 800 1,000 km are economcally best brdged by hgh voltage drect current (HVDC) power lnes, beng appled for decades for dstances of 2,000 km and more. HVDC power lnes show a power transmsson effcency of about 97% per 1,000 km. Below 800 1,000 km conventonal hgh voltage alternatng current (HVAC) power lnes represent the most cost effcent power transport soluton.[31]

11 Fgure 11: Aggregated people lvng n regons of least cost 100% renewable power supply and respectve dstance to these regons n dependence of fossl fuel prces n the range of USD/barrel eq n the year The evaluaton s based on least cost hybrd PV- Wnd-RPM-CCGT power plants (Fgure 10) and the dstrbuton of global populaton densty. Data for populaton densty are provded by Center for Internatonal Earth Scence Informaton Network (CIESIN) [41]. Wthn about 800 km to the regons of least cost 100% renewable power supply most people n the world could be suppled dependng on the fossl fuel prces,.e. about 85% of world populaton based on the least cost stuaton for 100 USD/barrel eq, about 90% for 150 USD/barrel eq, about 95% for 200 USD/barrel eq and about 98% for 250 USD/barrel eq. Comparng the results of the global energy supply potental of STEG versus hybrd PV-Wnd-RPM power plants shows the benefcal consequences of good solar and wnd resource potental accessble n many regons n the world. The supply potental for more than 90% of world populaton s lowered from 3,000 km to about 500 1,000 km. Ths reducton n dstance s very mportant for lowerng the poltcal obstacles for the ssues of transmttng large amounts of power through varous countres and the tme consumng constructon of HVDC power lnes. Moreover, the hybrd PV-Wnd-RPM power plants enable the 100% renewable power supply and guarantee the least LCOE opton. 8 Conclusons Renewable power methane storage enables bdrectonal lnkng of power and gas networks and represents a compettve seasonal storage opton. Due to a comparably low effcency of the full RPM process the cost of producng RPM s rather hgh. Therefore, LCOE of the nput power needs to be as low as possble. PV and wnd power reach qute compettve LCOE by the end of the 2010s, are abundantly avalable and show a hgh degree of complementarty n tme. However, both technologes are stll fluctuatng. Thus combnng low cost PV and wnd power wth the balancng RPM storage to hybrd PV-Wnd-RPM-CCGT power plants represents a new power opton for a 100% renewable energy supply. By the end of the 2010s, economcs of hybrd PV-Wnd- RPM power plants are very promsng n all regons of good solar and wnd resource qualty. The hybrd PV- Wnd-RPM-CCGT power plants mght represent the fundamental centrepece of sustanable and low cost power supply n the years to come. By the year 2020 about 90% of manknd mght be n reach to be suppled by 100% renewable power fully compettve to fossl fuel prces of about 150 USD/barrel eq and for practcally unlmted amounts of sustanably provded energy. The RPM approach enables long-term cost stablty due to a fully decoupled cost structure from fossl fuels, no net CO 2 emssons and enormous power supply potental offerng long-term and sustanable economc growth. Ths hybrd plant topology mght emerge nto the role of the key energy supply cornerstone n the world, n partcular f manknd ntends to economcally survve peak-ol and physcally and economcally survve clmate change. Acknowledgements The author would lke to thank Joachm Reß, Tll Utermöhlen and Ina von Spes for ther organzatonal support and Markus Hlusak and Domnk Huljć for contrbuton and helpful dscussons. References [1] [EPIA] European Photovoltac Industry Assocaton, Global Market Outlook for Photovoltacs untl 2015, EPIA, Brussels, [2] [GWEC] - Global Wnd Energy Councl, Global Wnd 2009 Report, GWEC, Brussels, 2010, Global_Wnd_2007_report/GWEC_Global_Wnd_ 2009_Report_LOWRES_15th.%20Apr.pdf [3] Breyer Ch., Gerlach A., Schäfer D., Schmd J., Fuel-Party: New Very Large and Sustanable Market Segments for PV Systems, IEEE EnergyCon, Manama, December [4] Breyer Ch., Görg M., Schmd J., Fuel- Party: Impact of Photovoltac on global fossl fuel fred power plant busness, 26. Symposum Photovoltasche Solarenerge, Bad Staffelsten, March 2-4 [5] Breyer Ch., Görg M., Gerlach A.-K., Schmd J., Economcs of Hybrd PV-Fossl Power Plants, ths conference [6] Breyer Ch., Economcs of Hybrd Photovoltac Power Plants, Dssertaton, Unversty of Kassel [7] Gerlach A.-K., Stetter D., Schmd J., Breyer Ch., PV and Wnd Power Complementary Technologes, ths conference [8] [IEA] - Internatonal Energy Agency, World Energy Outlook 2010, IEA, Pars [9] Sterner M., Boenergy and renewable power methane n ntegrated 100% renewable energy systems, Dssertaton, Unversty of Kassel

12 [10] Specht M., Sterner M., Stürmer B., Frck V., Hahn B., Renewable Power Methane - Stromspecherung durch Kopplung von Strom- und Gasnetz - Wnd/PV-to-SNG, Patent No: , patent fled n March 9 [11] Specht M., Brellochs J., Frck V., Stürmer B., Zuberbühler U., Sterner M., Waldsten G., Specherung von Boenerge und erneuerbarem Strom m Erdgasnetz, Erdöl Erdgas Kohle, 2010(10), [12] Sterner M., Sant-Drenan Y.-M., Gerhardt N., Specht M., Stürmer B., Zuberbühler U., Erneuerbares Methan Ene Lösung zur Integraton und Specherung Erneuerbarer Energen und en Weg zur regeneratven Vollversorgung, Solarzetalter, 2010(1), [13] Band A., Specht M., Wemer T., Schaber K., CO 2 Recyclng for Hydrogen Storage and Transportaton Electrochemcal CO 2 Removal and Fxaton, Energy Converson and Management, 36, [14] Arnhold O. and Möhrke F., Moblty Concepts for the Use of Excess Power from the Renewable Energy System on the Island of Gracosa (Azores Archpelago), 6 th Internatonal Renewable Energy Storage Conference, Berln, November 28-30, accepted [15] Jacobson M.Z. and Delucch M.A., A Path to Sustanable Energy by 2030, Scentfc Amercan, 2009(11), [16] Wengart J.M., The Helos Strategy: An Heretcal Vew of the Potental Role of Solar Energy n the Future of a Small Planet, Technologcal Forecastng and Socal Change, 12, [17] [WBGU] German Advsory Councl on Global Change, World n Transton: Towards Sustanable Energy Systems, WBGU, Berln, Earthscan, London, ntlchungen/hauptgutachten/jg2003/wbgu_jg2003_ engl.pdf [18] [WBGU] German Advsory Councl on Global Change, Welt m Wandel: Gesellschaftsvertrag für ene Große Transformaton, WBGU, Berln, ntlchungen/hauptgutachten/jg2011/wbgu_jg2011.p df [19] Teske S., Schäfer O., Zervos A., Béranek J., Tunmore S., Krewtt W., Smon S., Pregger T., Schmd S., Graus W., Blomen W., energy [r]evoluton: A Sustanable World Energy Outlook, Greenpeace Internatonal and EREC, Amsterdam and Brussels, October, ew-global-energy-r-evoluton.pdf [20] Sawn J.L. and Moomaw W.R., An endurng energy future, n: Sarke L. (ed.): State of the World: Into a Warmng World, The Worldwatch Insttute, Washngton, dg [21] Lu X., McElroy M.B., Kvluoma J., Global potental for wnd-generated electrcty, Proceedngs of the Natonal Academy of Scence, PNAS early edton, [22] [IPCC] - Intergovernal Panel on Clmate Change, Specal Report on Renewable Energy Sources and Clmate Change Mtgaton (SRREN), IPCC WG III Mtgaton of Clmate Change, Geneva, [23] Kohn W., A world powered predomnantly by solar and wnd energy, n: Schellnhuber, H.J., Molna, M., Stern, N., Huber, V., Kadner, S., (eds.), Global Sustanablty A Nobel Cause, Cambrdge Unversty Press, Cambrdge [24] Hubbert M.K., Energy from Fossl Fuels, Scence, 109, [25] Short W., Packey D.J., Holt T., A Manual for the Economc Evaluaton of Energy Effcency and Renewable Energy Technologes, NREL, NREL/TP , Golden [26] Stackhouse P.W., Whtlock C.H., (eds.), Surface meteorology and Solar Energy (SSE) release 6.0, NASA SSE 6.0, Earth Scence Enterprse Program, Natonal Aeronautc and Space Admnstraton (NASA), Langley, [27] Breyer Ch. and Schmd J., Populaton Densty and Area weghted Solar Irradaton: global Overvew on Solar Resource Condtons for fxed tlted, 1-axs and 2-axes PV Systems, 25 th EU PVSEC/ WCPEC-5, Valenca, September 6-10, DOI: /25thEUPVSEC2010-4BV.1.91 [28] Platts, UDI World Electrc Power Plants data base, Platts A Dvson of The McGraw-Hll, Washngton, verson of March 31 [29] Knes G. (ed.), Clean Power from Deserts The Desertec Concept for Energy, Water and Clmate Securty, Whtebook 4 th Ed., DESERTEC Foundaton, Hamburg, [30] Treb F., Schllngs C., Kronshage S., Klann U., Vebahn P., May N., Wlde R., Paul C., Kabart M., Bennouna A., Nokraschy El H., Hassan S., Yussef L.G., Hasn T., Bassam El N., Concentratng Solar Power for the Medterranean Regon, German Aerospace Center (DLR) by order of Federal Mnstry for the Envronment (BMU), Berln, [31] Treb F., Schllngs C., Kronshage S., Vebahn P., May N., Paul C., (eds.), Trans-Medterranean Interconnecton for Concentratng Solar Power, Research of German Aerospace Center (DLR) by order of Federal Mnstry for the Envronment, Nature Conservaton and Nuclear Safety, Berln, [32] Czsch G., Szenaren zur zukünftgen Stromversorgung - Kostenoptmerte Varatonen zur Versorgung Europas und sener Nachbarn mt Strom aus erneuerbaren Energen, Dssertaton, Unversty of Kassel, kassel.de/btstream/urn:nbn:de:hebs: /1/dssverson0502.pdf [33] Sörgel H., Atlantropa, Fretz & Wasmuth, Zürch [34] Vogt W., Atlantropa. Weltbauen am Mttelmeer. En Archtektentraum der Moderne, Grosser + Sten, Pforzhem [35] Schottky W., Photoelectrc Generator, US Patent 2,040,632, fled n May 1